This invention relates to a device for the actuation of clutch and, in particular, to a device for spring power supported operation of a motor vehicle clutch.
Devices of this kind are known in a variety of forms in prior art and are used in huge quantities the motor industry. With these devices the actuating force to be applied to the clutch pedal for disengaging the clutch, which at the required high contact pressures of clutches on modern high performance engines is correspondingly great, is reduced to a reasonable level by a spring acting upon the clutch pedal.
For example, the printed publications DE 29 23 027 C2, DE 36 36 748 C1, DE 38 41 719 C2, DE 41 10 476 A1, DE 44 35 260 A1, DE 196 50 577 A1 or U.S. Pat. No. 3,430,512 disclose devices for actuating a motor vehicle clutch, which in each case have a pivoted clutch pedal, connected to the piston rod of a hydraulic cylinder in order to create an actuating pressure. The clutch pedal is tiltable between two end settings or positions, of which one corresponds to the engaged condition of the clutch and the other to the disengaged condition. In addition, these devices each have at least one pivoted top dead centre spring installed, articulated with the clutch pedal in such a way that when the clutch pedal is in a position between one dead centre point on the one hand (where the effective line of the top dead centre spring, which also tilts due to its articulation with the clutch pedal when the clutch pedal is tilted, passes through the pivot point of the clutch pedal) and, on the other hand, one of the end positions, it exerts a force on the clutch pedal in the direction of this end position.
In this prior art, both the clutch pedal and the top dead centre spring are pivoted on a pedal frame or a specially-provided frame. A disadvantage of this prior art is that installation of the device on the vehicle is relatively difficult, especially at the beginning of the motor vehicle manufacturer""s assembly line.
As compared with the prior art described in the introduction in accordance with, for example, DE 29 23 027 C2, the invention is therefore based upon the problems of creating a simple device for operating a clutch which can easily be mounted at the particular place of assemblyxe2x80x94for example on the fixed pedal frame of a motor vehicle.
This problem is solved by the characteristics specified in patent claim 1. Beneficial or appropriate further developments of the invention are the subject of patent claims 2 to 10.
In the case of a device for actuating particularly a motor vehicle clutch which has an operating lever mounted pivoted at a bearing point, the operating lever being effectively connected to a master cylinder for producing an actuating pressure, and which has a top dead centre spring pivoted at another bearing point and connected to the operating lever in such a way that when the operating lever is in a position between a dead centre position and an end position it exerts a force on the operating lever in the direction of this end position, according to the invention both the bearing point for the top dead centre spring and also the other bearing point for the operating lever are provided on the master cylinder.
The top dead centre spring, which is completely pre-assembled and can therefore be installed into the motor vehicle easily and quickly, particularly in the motor vehicle manufacturer""s assembly line, but also when retrofitting or replacing, without the use of special tools, e.g., for pre-tensioning the top dead centre spring. The associated benefits in terms of logistics and costs are self-evident.
If the installation or the pre-tensioning of the top dead centre spring is carried out during pre-assembly of the actuating device as described in the invention, during installation of the actuating device in the motor vehicle the parts which move relative to the master cylinder, namely the operating lever and the top dead centre spring, are situated in their respective end positions due to the pre-tensioning of the top dead centre spring, and this corresponds to the engaged or disengaged condition of the clutch when the actuating device is installed, i.e., they are in a specific position relative to one another, which is beneficial in that it favours automated assembly of the securing device in the motor vehicle. If at the same time the pre-tensioned operating lever is in its end position which will later correspond to the disengaged condition of the clutch, the actuating device will be particularly compact for installation, which is an advantage. After installation of the actuating device, the operating lever only has to be pulled back to its start position for filling the hydraulic clutch actuating system, i.e., pulled back to the other end position, which corresponds to the engaged position of the clutch.
A particular advantage of the actuating device as described in the invention also lies in that the pedal frame to be installed in the motor vehicle can be of optimised design regarding its weight, its size and the installation space it requires, as well as its production costs, because all the swivel bearing points needed for the functioning of the actuating device are present on the master cylinder. It is thus possible to design the pedal frame solely for the bearing arrangement of the accelerator pedal and the brake pedal, only simple measures (e.g., suitable bores) being provided for on the pedal frame in order to allow securing of the actuating device described in the invention to the pedal frame. The result is that one and the same pedal frame can be used both for motor vehicles with automatic clutch actuation or automatic gear boxes (clutch pedal not needed) and also for motor vehicles with conventional clutch actuation (clutch pedal needed). With the platform method of construction which is widespread in the motor industry, where in particular the chassis, engine and drive train are identical for various model series, this becomes an even greater advantage.
It is also possible to accommodate the actuating device described in the invention, which is functionally independent, according to the requirements in each particular case, so that it is spatially separated from the pedal frame in the motor vehicle. With the actuating device as defined in the invention, increased spatial flexibility therefore exists, as compared with the prior art described in the introduction. A beneficial accompanying effect here, finally, is also that the pedal frame is eliminated as a system component common to the clutch system and the braking system, so that appropriate mutual harmonisation of these systems, which differ especially with regard to safety requirements, is no longer necessary.
According to certain aspects of an embodiment of the present invention, the bearing point provided for on the master cylinder for the top dead center spring and/or the bearing point provided for on the master cylinder for the operating lever is/are at the same time designed as a securing point, which serves for securing on a pedal frame the pre-assembled composite unit consisting of the master cylinder, the operating lever and the top dead center spring. This design of the actuating device not only reduces the number of parts needed for securing to the pedal frame and the number of securing points for the pedal frame, but also has the advantage, compared with the prior art described above in accordance with DE 36 36 748 C1 or DE 41 10 476 A1, for example, that the securing points are located at pre-determined or defined points on the actuating device, the relative position of which to the master cylinder is completely independent of the relative position of the operating lever or the top dead center spring to the master cylinder. This again considerably simplifies and speeds up installation of the actuating device on the pedal frame, because the operating lever does not first have to be brought into a particular position for this purpose, as was necessary with the prior art cited above. An additional benefit is derived from the fact that the forces applied via the operating lever and by the top dead center spring can be supported in the assembled condition of the actuating device on the pedal frame, allowing the master cylinder housing to be optimized as regards weight, or to be built in lightweight construction, particularly of plastic.
According to certain other aspects of an embodiment of the present invention, the bearing point for the operating lever has a collar sleeve preferably made of metal, the middle section of which passes through a bearing eye provided on the master cylinder housing as well as a bore in the operating lever, and is provided with a ring collar on each of the two sides of its middle section, in order to maintain the swiveling capability of the which penetrates the collar sleeve, and the head of the screw grasps the collar sleeve on the side facing away from the pedal frame, in order to secure the pre-assembled composite unit consisting of the master cylinder, the operating lever and the top dead center spring to the pedal frame.
According to another aspect of an embodiment of the present invention, the bearing point for the operating lever is appropriately designed on a strut formed integral with the master cylinder housing which extends from one of the longitudinal sides of the master cylinder housing, creating in a simple way the required distance between the bearing point around which the operating lever pivots and the point of articulation of the master cylinder piston rod with the operating lever.
According to other aspects of an embodiment of the present invention, the top dead center spring is pivoted on the master cylinder housing, with one end on the longitudinal side of the master cylinder housing, from which the strut extends, and the operating lever is formed as an angle with two legs. The other end of the top dead center spring is articulated with the second leg of the operating lever and the master cylinder is effectively connected by means of its piston rod with the first leg of the operating lever, whilst the operating lever itself is pivoted at the connection point of the leg on the bearing point of the strut. With this design of the actuating device, wherein the operating lever when in the installed position can be arranged essentially parallel with the master cylinder housing or, seen from the direction of the operating lever, can be arranged at the side of the master cylinder, it is an advantage if the actuating device is of particularly flat construction.
Finally, according to an alternative design, the top dead center spring is pivoted on the master cylinder housing, with one end on the longitudinal side of the master cylinder housing facing away from the strut, and the operating lever is formed as an angle with two legs. Here, the other end of the top dead center spring is articulated with the first leg of the operating lever and the master cylinder is effectively connected by means of its piston rod with the operating lever at the connection point of the leg, whilst the operating lever itself is pivoted on the second leg at the bearing point of the strut. With this design of the actuating device, wherein the operating lever can be arranged in the same plane as the master cylinder and the top dead center spring when in the installed position, and when seen from the direction of the operating lever, can be arranged beneath the master cylinder, it is an advantage if the actuating device is of particularly narrow construction. The invention is explained in greater detail below, using preferred embodiments, with reference to the attached drawings.